<template>
    <div class="div" @click="createdCode">
      <canvas id="div" :width="contentWidth" :height="contentHeight" />
    </div>
  </template>
  <script>
  import Vue from 'vue'
  export default Vue.extend({
    props: {
      fontSizeMin: {
        type: Number,
        default: 25
      },
      fontSizeMax: {
        type: Number,
        default: 30
      },
      backgroundColorMin: {
        type: Number,
        default: 255
      },
      backgroundColorMax: {
        type: Number,
        default: 255
      },
      colorMin: {
        type: Number,
        default: 0
      },
      colorMax: {
        type: Number,
        default: 160
      },
      lineColorMin: {
        type: Number,
        default: 100
      },
      lineColorMax: {
        type: Number,
        default: 255
      },
      dotColorMin: {
        type: Number,
        default: 0
      },
      dotColorMax: {
        type: Number,
        default: 255
      },
      contentWidth: {
        type: Number,
        default: 90
      },
      contentHeight: {
        type: Number,
        default: 30
      }
    },
    data() {
      return {
        identifyCode: ''
      }
    },
    mounted() {
      this.createdCode()
    },
    methods: {
      // 生成4个随机数
      createdCode() {
        const len = 4
        const codeList = []
        const chars = 'ABCDEFGHJKMNPQRSTWXYZabcdefhijkmnprstwxyz01234569'
        const charsLen = chars.length
        for (let i = 0; i < len; i++) {
          codeList.push(chars.charAt(Math.floor(Math.random() * charsLen)))
        }
        this.identifyCode = codeList.join('')
        this.$emit('getIdentifyCode', this.identifyCode.toLowerCase())
        this.drawPic()
      },
   
      // 生成一个随机数
      randomNum(min, max) {
        return Math.floor(Math.random() * (max - min) + min)
      },
      // 生成一个随机的颜色
      randomColor(min, max) {
        const r = this.randomNum(min, max)
        const g = this.randomNum(min, max)
        const b = this.randomNum(min, max)
        return 'rgb(' + r + ',' + g + ',' + b + ')'
      },
   
      drawPic() {
        const canvas = document.getElementById('div')
        const ctx = canvas.getContext('2d')
        ctx.textBaseline = 'bottom'
        // 绘制背景
        ctx.fillStyle = this.randomColor(
          this.backgroundColorMin,
          this.backgroundColorMax
        )
        ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
        // 绘制文字
        for (let i = 0; i < this.identifyCode.length; i++) {
          this.drawText(ctx, this.identifyCode[i], i)
        }
        this.drawLine(ctx)
        // this.drawDot(ctx)
      },
   
      drawText(ctx, txt, i) {
        ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
        ctx.font =
          this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei'
        const x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
        const y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
        var deg = this.randomNum(-45, 45)
        // 修改坐标原点和旋转角度
        ctx.translate(x, y)
        ctx.rotate((deg * Math.PI) / 180)
        ctx.fillText(txt, 0, 0)
        // 恢复坐标原点和旋转角度
        ctx.rotate((-deg * Math.PI) / 180)
        ctx.translate(-x, -y)
      },
   
      // 绘制干扰线
      drawLine(ctx) {
        for (let i = 0; i < 5; i++) {
          ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax)
          ctx.beginPath()
          ctx.moveTo(
            this.randomNum(0, this.contentWidth),
            this.randomNum(0, this.contentHeight)
          )
          ctx.lineTo(
            this.randomNum(0, this.contentWidth),
            this.randomNum(0, this.contentHeight)
          )
          ctx.stroke()
        }
      },
   
      // 绘制干扰点
      drawDot(ctx) {
        for (let i = 0; i < 80; i++) {
          ctx.fillStyle = this.randomColor(0, 255)
          ctx.beginPath()
          ctx.arc(
            this.randomNum(0, this.contentWidth),
            this.randomNum(0, this.contentHeight),
            1,
            0,
            2 * Math.PI
          )
          ctx.fill()
        }
      }
    }
  })
  </script>
   <style scoped>
  .div {
    margin: 0;
    padding: 0;
    height: 18px;
  }
  .div canvas {
    margin-top: 0px;
    margin-left: 6px;
    height: 27px;
  }
  </style>